Tropical Gardening Helpline: Myriad reasons some seedlings fail

  • In some forms of damping off disease a white mycelia appears on the soil around the seedling. (Photos courtesy / umn.edu)
  • Damping off disease causes the stems of a seedling to literally rot at the base and die. (Photos courtesy / extension.umn.edu)
  • Damping off disease is caused by a soil borne fungus that kills seedlings shortly after they emerge. (Photos courtesy / planetnatural.com)

Merrilyn asks: My summer veggie garden is failing at the seedling stage. Some seeds don’t germinate at all; those that do germinate and produce seedlings wilt and die within a few days. What’s up with this?

Tropical Gardener Answer: Glad to hear you are planting vegetable seeds. Sorry for your problems. Several things may be going on. I will give you some possibilities and some treatments and you can hopefully figure out which is your problem and proceed with the correct treatment.

ADVERTISING


Geckos, rats, mice and some large beetles may, in fact, be eating your seeds. I recently experienced this with some squash and cacao seeds. You will likely see evidence of something doing some digging in your seeding pots. The soil will be disturbed a bit. If you suspect this, choose one pot to pour out and see if you see any seeds. If not, I suspect a critter has stolen them. Plant again and cover your trays well to keep critters out.

If your non-germinated seeds are still present in the soil, you may have either overwatered or underwatered the medium. Lack of germination could be evidence of the seed being too wet and rotting or being too dry to germinate. If you find a seed, you can determine by feeling it whether it is too wet or too dry. The correct moisture level for a seeding mix is comparable to that of a wrung out sponge. Damp but not wet.

If you put the seeds in a thoroughly wet medium to start with and then only lightly spray the top of the soil daily after that, you should see successful germination in a few weeks. Some seeds do take a lot longer, so look up the germination rate on the particular seed you have planted. Those are usually available on the seed packet or on the internet.

In some cases of germination failure, temperature may be a factor. Tropical plants, like cacao, will germinate best when the seeding medium is warm. Choose a warm place inside or get a seedling heat mat. Many waterproof ones are available online.

The second issue you mentioned, where the seeds do germinate but then the seedlings wilt and die quickly, is a common problem caused by a soil fungus. The disease is known as damping off. It causes the stems to become thin and brown and the seedlings to keel over. Sometimes the disease develops white fluffy fungi on top of the soil as well. Wet, cool conditions can encourage these fungi.

Always start seeds in a sterile seeding mix when possible. You can sterilize your own soil by cooking it if you like. Find and follow direction for doing this online. It is also important that you start seeds in an area that is not exposed to rain. You want to control the amount of water the seeds get so they don’t rot or succumb to a fungal disease.

A few other natural practices have demonstrated success in preventing damping off. A thin layer of vermiculite seems to prevent the fungus from spreading on the soil surface. Many gardeners have also reported success by watering seedlings lightly with chamomile tea or sprinkling cinnamon on the soil. The anti-fungal properties of chamomile or cinnamon seem to prevent “damping off.”

Hopefully these suggestions will help you figure out the problem with your seedlings. Don’t despair. Here in Hawaii, you still have plenty of time to get your veggies going.

Email plant questions to konamg@ctahr.hawaii.edu for answers by Certified Master Gardeners. Some questions will be chosen for inclusion in this column.

Diana Duff is a plant adviser, educator and consultant living in a dryland forest north of Kailua-Kona.

Gardening Events

Thursday: “Coffee Pruning Strategies Field Day” from 9-11 a.m. or 1-3 p.m. at the Kona Cooperative Extension Office 79-7381 Mamalahoa Highway across from the Aloha Theatre in Kainaliu with Dr. Stuart T. Nakamoto and Andrea Kawabata of UH CTAHR. Free, but registration is required. Go to https://bit.ly/2IB8qgv or contact Gina at 322-4892 at least two days prior.

Saturday: “Work Day at Amy Greenwell Garden” from 9 a.m. to 12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Volunteers will be able to help with garden maintenance and are invited to bring a brown bag lunch. Water and snacks provided. Call Peter at 323-3318 for more information.

Farmer Direct Markets

Wednesday: “Ho’oulu Farmers Market” 9 a.m. to 2 p.m. at Sheraton Kona Resort &Spa at Keauhou Bay

“Sunset Farmers Market” 2-6 p.m. in the HPM parking lot at 74-5511 Luhia Street in Kailua-Kona (across from Target)

Saturday: “Keauhou Farmers Market” 8 a.m. to noon at Keauhou Shopping Center

“Kamuela Farmer’s Market” from 7 a.m. to noon at Pukalani Stables

“Waimea Town Market” from 7:30 a.m. to noon at the Parker School in central Waimea

“Waimea Homestead Farmers Market” from 7 a.m. to noon at the Waimea Middle and Elementary School Playground

Sunday: “Pure Kona Green Market” 9 a.m. to 2 p.m. at Amy Greenwell Garden in Captain Cook

“Hamakua Harvest” 9 a.m. to 2 p.m. at Hwy 19 and Mamane Street in Honokaa

Plant Advice Lines

Anytime: konamg@ctahr.hawaii.edu

ADVERTISING


Tuesdays &Thursdays: 9 a.m. to noon at UH-CES in Kainaliu – 322-4893

Mondays &Fridays: 9 a.m. to noon at UH CES at Komohana in Hilo 981-5199 or himga@hawaii.edu